The present invention relates to a photoelectric conversion apparatus for detecting the movement of an object.
As a conventional photoelectric conversion apparatus of this type, for example, Japanese Patent Publication No. 56-39429 discloses a photoelectric conversion apparatus for detecting the movement of an object, in which a large number of photoelectric conversion elements are connected in electrically positive and negative directions such that the elements connected in the positive and negative directions repeatedly appear on a plane in the longitudinal and lateral directions, and the sum of outputs from the photoelectric conversion elements in the positive direction and the sum of outputs from the photoelectric conversion elements in the negative direction are differentially connected to each other. With this arrangement, when an object to be detected is at rest, the two element outputs cancel each other, and hence no differential output is transmitted. When the object moves, pulse-like differential outputs are periodically output so that a detection output having a frequency corresponding to the moving speed of the object can be obtained.
In the above-described conventional photoelectric conversion apparatus, however, if photoelectric conversion elements and spatial filters for detecting the movement of a target object are integrally manufactured by using monocrystalline silicon members as photoelectric conversion components, an element formation process demands a large number of steps such as diffusion and etching. In addition, if such apparatuses are manufactured to have large areas, a reduction in yield is caused, resulting in an increase in cost. Furthermore, when active elements used for signal processing are integrated on a monocrystalline silicon layer, the portion on which the elements are formed cannot be used as a portion having light sensitivity.